[Svartalfiar]

There is no guarantee that family or gang shootings will not occur in public.

Correct, but the main differentiator is the target. Family/gang shootings are primarily targeted at certain family members, or members of a rival gang. If you're not the target, you'll be an incidental casualty. The gunman won't be aiming for you. The mass public shooting is one where the gunman is shooting at just about anything he sees moving - being in the vicinity makes you a target. So your odds of getting shot at are much higher.

[ding_dong_daddy_from_dumas]

The mass public shooting is one where the gunman is shooting at just about anything he sees moving

But why does the word "public" belong in a phrase that defines mass shootings that are neither family nor gang shootings? Wouldn't "targeting random victims" be more accurate than "public?"